Method for fingerprint unlocking and terminal

ABSTRACT

A method for fingerprint unlocking is provided. Whether fingerprint ridges of fingerprint images obtained are discontinuous or fuzzy is determined, in response to a fingerprint recognition module being detected to be pressed. If YES, Multiple fingerprint images are acquired, by acquiring fingerprints more than once with any first adjustment level selected from an ADC offset including M first adjustment levels and any second adjustment level selected from an ADC gain including N second adjustment levels. Multiple image quality evaluation values are obtained, by performing an image quality evaluation on each of the plurality of fingerprint images according to one or more image quality evaluation indexes, and a fingerprint image corresponding to a maximum image quality evaluation value is selected as a target fingerprint image. A terminal is unlocked when the target fingerprint image matches a preset fingerprint image successfully. A terminal is also provided.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.16/119,111, filed on Aug. 31, 2018, which is a continuation ofInternational Application No. PCT/CN2017/079612, filed on Apr. 6, 2017,which claims priority to Chinese Patent Application No. 201610218370.1,filed on Apr. 8, 2016, the contents of all of which are hereinincorporated by reference in their entireties.

TECHNICAL FIELD

This disclosure relates to the technical field of terminal device, andparticularly to a method for fingerprint unlocking and a terminal.

BACKGROUND

With rapid development of information technology, terminals (such asmobile phones, tablet computers, etc.) are more and more widely used.Fingerprint recognition technology serving as a standard configurationof the terminal has been widely applied to unlock the terminal, wakeupthe terminal, mobile payment, and so on. Whilst the fingerprintrecognition technology is popular, unlocking time of the terminal is anissue that is directly concerned by terminal manufacturers in order toachieve quick unlocking.

In actual use, when a finger of a user is over-dry or over-wet, the userhas to press a fingerprint recognition module of the terminal for manytimes to make it possible for successful unlocking. Thus, the efficiencyof fingerprint unlocking is disadvantageously affected.

SUMMARY

Implementations of the present disclosure provide a method forfingerprint unlocking and a terminal.

According to a first aspect of the implementations of the presentdisclosure, there is provided a method for fingerprint unlocking. Themethod includes the follows.

Whether fingerprint ridges of fingerprint images obtained arediscontinuous or fuzzy is determined in response to a fingerprintrecognition module being detected to be pressed.

Multiple fingerprint images are obtained, by acquiring fingerprints morethan once with any first adjustment level selected from ananalog-to-digital converter (ADC) offset including M first adjustmentlevels and any second adjustment level selected from an ADC gainincluding N second adjustment levels, based on a determination that thefingerprint ridges of the fingerprint images obtained are discontinuousor fuzzy. M and N are integers greater than 1.

Multiple image quality evaluation values are obtained, by performing animage quality evaluation on each of the plurality of fingerprint imagesaccording to one or more image quality evaluation indexes, and afingerprint image corresponding to a maximum image quality evaluationvalue is selected as a target fingerprint image. The image qualityevaluation indexes include image clarity, signal-to-noise ratio (SNR),ridge resolution, fingerprint image coverage rate, contrast ratio, andaverage gray scale.

A terminal is unlocked when the target fingerprint image matches apreset fingerprint image successfully.

According to a second aspect of the implementations of the presentdisclosure, there is provided a terminal. The terminal includes ajudging unit, an obtaining unit, a determining unit, and an unlockingunit.

The judging unit is configured to judge whether a finger pressing afingerprint recognition module is a dry finger or a wet finger, inresponse to the fingerprint recognition module being detected to bepressed.

The obtaining unit is configured to obtain multiple fingerprint images,by acquiring fingerprints more than once with any first adjustment levelselected from an analog-to-digital converter (ADC) offset including Mfirst adjustment levels and any second adjustment level selected from anADC gain including N second adjustment levels, based on a determinationthat the finger pressing the fingerprint recognition module is a dryfinger or a wet finger. M and N are integers greater than 1.

The determining unit is configured to obtain multiple image qualityevaluation values, by performing an image quality evaluation on each ofthe plurality of fingerprint images according to one or more imagequality evaluation indexes, and select a fingerprint image correspondingto a maximum image quality evaluation value as a target fingerprintimage. The image quality evaluation indexes include image clarity,signal-to-noise ratio (SNR), ridge resolution, fingerprint imagecoverage rate, contrast ratio, and average gray scale.

The unlocking unit is configured to unlock the terminal when the targetfingerprint image determined by the determining unit matches a presetfingerprint image successfully.

According to a third aspect of the implementations of the presentdisclosure, there is provided a terminal. The terminal includes a memorystoring executable program codes and a processor coupled with thememory. The processor is configured to evoke the executable programcodes stored in the memory to carry out all or part of the actions ofany method according to the first aspect of the implementations of thepresent disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to illustrate technical solutions of implementations of thepresent disclosure more clearly, the drawings used in theimplementations will be briefly described below. It will be apparentthat the drawings described in the following are merely someimplementations of the present disclosure, and it will be apparent tothose skilled in the art that other drawings can be obtained from thedrawings without any creative work.

FIG. 1A is a schematic flow chart illustrating a method for fingerprintunlocking according to a first method implementation of the presentdisclosure.

FIG. 1B is a schematic flow chart illustrating a method for fingerprintunlocking according to a second method implementation of the presentdisclosure.

FIG. 2A shows an example of fingerprint ridges of a dry finger.

FIG. 2B shows an example of fingerprint ridges of a wet finger.

FIG. 2C shows an example of fingerprint ridges of a normal finger.

FIG. 3A is a schematic flow chart illustrating a method for fingerprintunlocking according to a third method implementation of the presentdisclosure.

FIG. 3B is a schematic flow chart illustrating a method for fingerprintunlocking according to a fourth method implementation of the presentdisclosure.

FIG. 4 is a schematic structural diagram illustrating a terminalaccording to a first terminal implementation of the present disclosure.

FIG. 5 is a schematic structural diagram illustrating a terminalaccording to a second terminal implementation of the present disclosure.

DETAILED DESCRIPTION

Implementations of the present disclosure provide a method forfingerprint unlocking and a terminal, which can improve the efficiencyof fingerprint unlocking.

Technical solutions of the present disclosure will be described clearlyand completely with reference to the accompanying drawings; obviously,the implementations described below are merely part of rather than allof the implementations of the present disclosure. Based on theimplementations of the present disclosure, other implementationsobtained there from without any creative work by those of ordinary skillin the art shall fall into the protection scope of the presentdisclosure.

The terms “first”, “second”, “third”, “fourth”, and the like in thespecification and claims of the present disclosure and the drawings areused to distinguish different objects rather than describe a specificorder. In addition, terms of “including” and “having” and any inflexionsthereof are intended to cover a non-exclusive inclusions relationship.For example, processes, methods, systems, products or devices containinga series of operations or units are not limitative to listed processesor units, other processes or units which are not listed can also beincluded, or other processes or units inherent to these processes,methods, products or devices can also be included.

The term “embodiment” or “implementation” referred to herein means thata particular feature, structure, or feature described in conjunctionwith the implementation may be contained in at least one implementationof the present disclosure. The phrase appearing in various places in thespecification does not necessarily refer to the same implementation, nordoes it refer to an independent or alternative implementation that ismutually exclusive with other implementations. It is expressly andimplicitly understood by those skilled in the art that an implementationdescribed herein may be combined with other implementations.

A terminal illustrated in the implementations of the present disclosuremay include a smart phone (e.g., Android® phone, iOS® phone, Windows®Phone, etc.), a tablet computer, a palmtop computer, a laptop computer,a mobile internet device (MID) or a wearable device. The foregoingterminal is only exemplary rather than exhaustive. The presentdisclosure includes but is not limited to the foregoing terminal.

A fingerprint recognition module in the implementations of the presentdisclosure may mainly include a coating, a sensor, and a fingerprintacquisition chip. The coating is configured to protect the sensor andthe fingerprint acquisition chip. The sensor and the fingerprintacquisition chip are core components of the fingerprint recognitionmodule, which are configured for fingerprint acquisition andrecognition.

According to a first aspect of the implementations of the presentdisclosure, there is provided a method for fingerprint unlocking. Themethod includes: obtaining multiple fingerprint images, by acquiringmultiple sets of fingerprints through adjusting adjustment parameters ofa fingerprint acquisition chip of a fingerprint recognition module morethan once, in response to detecting that the fingerprint recognitionmodule is pressed, each fingerprint image corresponding to each set offingerprints, the each set of fingerprints corresponding to adjustmentparameters adjusted each time; determining a target fingerprint imagewith the best image quality from the plurality of fingerprint images;unlocking a terminal when the target fingerprint image matches a presetfingerprint image successfully.

According to a second aspect of the implementations of the presentdisclosure, there is provided a terminal. The terminal includes at leastone processor and a computer readable storage. The computer readablestorage is coupled to the at least one processor and stores at least onecomputer executable instruction thereon, which when executed by the atleast one processor, cause the at least one processor to carry outactions, including: obtaining multiple fingerprint images, by acquiringfingerprints multiple sets of through adjusting adjustment parameters ofa fingerprint acquisition chip of a fingerprint recognition module morethan once, in response to detecting that the fingerprint recognitionmodule is pressed, each fingerprint image corresponding to each set offingerprints, the each set of fingerprints corresponding to adjustmentparameters adjusted each time; determining a target fingerprint imagewith the best image quality from the plurality of fingerprint images;unlocking a terminal when the target fingerprint image matches a presetfingerprint image successfully.

According to a third aspect of the implementations of the presentdisclosure, there is provided a non-transitory computer-readable storagemedium storing a computer program which, when executed by a processor,causes the processor to carry out actions: obtaining a plurality offingerprint images, by acquiring a plurality of sets of fingerprintsthrough adjusting adjustment parameters of a fingerprint acquisitionchip of a fingerprint recognition module more than, in response todetecting that the fingerprint recognition module is pressed, eachfingerprint image corresponding to each set of fingerprints, the eachset of fingerprints corresponding to adjustment parameters adjusted eachtime; determining a target fingerprint image with the best image qualityfrom the plurality of fingerprint images; unlocking a terminal when thetarget fingerprint image matches a preset fingerprint imagesuccessfully.

Referring to FIG. 1A, FIG. 1A is a schematic flow chart illustrating amethod for fingerprint unlocking according to a first methodimplementation of the present disclosure. The method for fingerprintunlocking described in the implementation of the present disclosurestarts with operations at block 101.

At block 101, multiple fingerprint images are obtained, by acquiringmultiple sets of fingerprints through adjusting adjustment parameters ofa fingerprint acquisition chip of a fingerprint recognition module morethan once, in response to detecting that the fingerprint recognitionmodule is pressed, where each fingerprint image corresponds to each setof fingerprints and the each set of fingerprints corresponds toadjustment parameters adjusted each time.

In the implementation of the present disclosure, when detecting that thefingerprint recognition module is pressed, the fingerprint recognitionmodule can obtain the fingerprint images during the process of pressingthe fingerprint recognition module by the user. By acquiring thefingerprints through adjusting the adjustment parameters of thefingerprint acquisition chip of the fingerprint recognition module, themultiple fingerprint images can be obtained with different adjustmentparameters.

In an implementation, the adjustment parameters of the fingerprintacquisition chip of the fingerprint recognition module mainly include ananalog-to-digital converter (ADC) offset and an ADC gain. The ADC offsetis configured to indicate an offset of an ADC. For example, afingerprint acquisition chip can collect 56*172 pixel points, with eachpixel point corresponding to a pixel value in an image collectionprocess of the fingerprint acquisition chip, thus, totally 10752 pixelvalues can be obtained. After the pixel values are normalized, that is,when the pixel values fall within a range from 0 to 1 (0-1), normally,most of the pixel values are distributed within a range from 0.4 to 0.8(0.4-0.8). Since the pixel value of each pixel point is different, apixel point distribution diagram may be formed. The ADC offset may haveseveral grades, when the value of the ADC offset is higher, an overallpixel value corresponding to the pixel point distribution diagram islarger, and a fingerprint image will appear darker. The ADC gain isconfigured to indicate a gain of the ADC. When the gain is larger, thedistribution diagram will be more dispersed. Similarly, when the gain issmaller, the distribution diagram will be more centralized. Further,when the distribution diagram is more dispersed, the image contrast willbe higher, black pixel points in the fingerprint image will be darker,and white pixel points in the fingerprint image will be whiter. Theadjustment parameters of the fingerprint acquisition chip in thefingerprint recognition module may further include a pixel gain, whichis configured to indicate a gain of a pixel point. The pixel gain isdetermined by capacitors coupled to an amplifier in parallel. A numberof capacitors are coupled to the amplifier in parallel, and eachcapacitor may be controlled by a switch. When the switch is turned onmore frequently, the gain will be larger, the pixel value will belarger, and the signal strength will be higher. In actual use, in an ADCcontrol process, the pixel gain is generally fixed, and the ADC offsetand ADC gain are mainly adjusted. The ADC offset is configured to adjustthe position of the whole distribution diagram, and the ADC gain isconfigured to adjust the concentration and dispersion of thedistribution diagram. For example, when the user presses the fingerprintrecognition module, image collection may be debugged by means ofdifferent adjustment parameters. For example, if the ADC offset and theADC gain each has five levels, twenty-five combinations can be obtained,and at most twenty-five fingerprint images can be collected (acquired)each time.

Furthermore, the adjustment parameters at least include the ADC offsetand the ADC gain. The ADC offset has M first adjustment levels, and theADC gain has N second adjustment levels. M and N are integers greaterthan 1. Thus, when the terminal detects that the fingerprint recognitionmodule is pressed, the multiple fingerprint images can be obtained byacquiring the fingerprints for several times with any first adjustmentlevel selected from the M first adjustment levels and any secondadjustment level selected from the N second adjustment levels. That is,when the terminal detects that the fingerprint recognition module ispressed, a fingerprint image can be obtained by acquiring thefingerprints with one first adjustment level selected from the M firstadjustment levels and one second adjustment level selected from the Nsecond adjustment levels. For example, when both M and N equal to 5,totally 25 fingerprint images can be obtained. In an implementation,three fingerprint images may be obtained. For example, three fingerprintimages, namely a first fingerprint image, a second fingerprint image,and a third fingerprint image, are obtained by adjusting the ADC offsetand the ADC gain. That is, the ADC offset is adjusted to the maximumlevel and the ADC gain is adjusted to the maximum level to obtain thefirst fingerprint image. The ADC offset is adjusted to the minimum leveland the ADC gain is adjusted to the minimum level to obtain the secondfingerprint image. The ADC offset is adjusted to the intermediate leveland the ADC gain is adjusted to the intermediate level to obtain thethird fingerprint image.

At block 102, a target fingerprint image with the best image quality isdetermined from the multiple fingerprint images.

In the implementation of the present disclosure, the terminal candetermine the target fingerprint image with the best image quality fromthe multiple fingerprint images. The terminal can perform an imagequality evaluation on each of the multiple fingerprint images accordingto one or more image quality evaluation indexes, to obtain multipleimage quality evaluation values. The terminal selects a fingerprintimage corresponding to a maximum image quality evaluation value as thetarget fingerprint image. The image quality evaluation indexes caninclude but not limit to image clarity, signal-to-noise ratio (SNR),ridge resolution, fingerprint image coverage rate, contrast ratio,average gray scale, and the like.

In one aspect, the terminal can perform an image quality evaluation oneach of the multiple fingerprint images according to a same imagequality evaluation index, to obtain a multiple image quality evaluationvalues. The terminal can select a fingerprint image corresponding to amaximum image quality evaluation value as the target fingerprint image.

In an implementation, the terminal can obtain clarity of each of themultiple fingerprint images and select a fingerprint image with thehighest image clarity as the target fingerprint image.

In an implementation, the terminal can obtain SNR of each of themultiple fingerprint images and select a fingerprint image with thehighest SNR as the target fingerprint image.

In an implementation, the terminal can obtain a fingerprint imagecoverage rate of each of the multiple fingerprint images and select afingerprint image with the highest fingerprint image coverage rate asthe target fingerprint image. As only part of the fingerprint imagerather than entire fingerprint image may include fingerprint ridges. Thefingerprint image coverage rate indicates a ratio of a fingerprint imagewith fingerprint ridges to the entire fingerprint image.

In an implementation, the terminal can obtain fingerprint image ridgeresolution of each of the multiple fingerprint images and select afingerprint image with the highest ridge resolution as the targetfingerprint image.

In another aspect, the terminal can perform an image quality evaluationon each of the multiple fingerprint images according to at least twoimage quality evaluation indexes, to obtain multiple image qualityevaluation values. The terminal selects a fingerprint imagecorresponding to a maximum image quality evaluation value as the targetfingerprint image. That is, the target fingerprint image with the bestimage quality is determined from the multiple fingerprint images byusing at least two image quality evaluation indexes configured toevaluate fingerprint images.

Specifically, an image quality evaluation value of each fingerprintimage of the multiple fingerprint images can be calculated with aformula

$S = {\sum\limits_{i = 1}^{K}{{\partial_{i}P_{i}}.}}$A fingerprint image corresponding to a maximum image quality evaluationvalue is used as the target fingerprint image. S represents (indicates)the image quality evaluation value, K represents the number of the imagequality evaluation indexes, P_(i) represents an image quality evaluationvalue corresponding to the i^(th) image quality evaluation index, ∂_(i)represents a weight of the i^(th) image quality evaluation index, and

${\sum\limits_{i = 1}^{K}\partial_{i}} = 1.$K is an integer greater than 1.

At block 103, the terminal is unlocked when the target fingerprint imagematches a preset fingerprint image successfully.

In the implementation of the present disclosure, when the targetfingerprint image matches the preset fingerprint image successfully,unlock the terminal.

When the target fingerprint image is compared with the presetfingerprint image, a matching value between the target fingerprint imageand the preset fingerprint image can be determined. When the matchingvalue reaches a certain threshold, it can be determined that the targetfingerprint image matches the preset fingerprint image successfully. Onthe other hand, when the matching value does not reach the certainthreshold, it can be determined that the target fingerprint image doesnot match the preset fingerprint image. When the target fingerprintimage is compared with the preset fingerprint image, fingerprint ridgesof the target fingerprint image can be compared with the fingerprintridges of the preset fingerprint image. When a matching value reaches acertain threshold, it can be determined that the fingerprint ridges ofthe target fingerprint image match the fingerprint ridges of the presetfingerprint image successfully. On the other hand, when the matchingvalue does not reach the certain threshold, it can be determined thatthe fingerprint ridges of the target fingerprint image do not match thefingerprint ridges of the preset fingerprint image. When the targetfingerprint image is compared with the preset fingerprint image, featurepoints such as Harris corners and scale-invariant feature transform(SIFT) corners of the target fingerprint image can be extracted. Featurepoints of the obtained target fingerprint image can be compared withfeature points of the preset fingerprint image. When a matching valuereaches a certain threshold, it can be determined that the featurepoints of the target fingerprint image are successfully matched with thefeature points of the preset fingerprint image. When the matching valuedoes not reach the certain threshold, it can be determined that thefeature points of the target fingerprint image do not match the featurepoints of the preset fingerprint image.

By means of the implementations of the present disclosure, in responseto detecting that a fingerprint recognition module is pressed, multiplefingerprint images are obtained, by acquiring fingerprints throughadjusting adjustment parameters of a fingerprint acquisition chip of thefingerprint recognition module. Further, a target fingerprint image withthe best image quality from the multiple fingerprint images isdetermined. Then, a terminal is unlocked when the target fingerprintimage matches a preset fingerprint image successfully. Therefore, thetarget fingerprint image with the best image quality can be obtained byadjusting the adjustment parameters. When the target fingerprint imageis compared with the preset fingerprint image, the matching success ratebetween the two can be improved, that is, the efficiency of fingerprintunlocking can be improved. In particular, when the fingerprints of theuser's finger are fingerprints of a dry finger or fingerprints of a wetfinger, the number of times that the user presses the fingerprintrecognition module can be reduced, and thus, the efficiency offingerprint unlocking is improved, and time consumed by fingerprintunlocking is reduced.

Referring to FIG. 1B, FIG. 1B is a schematic flow chart illustrating amethod for fingerprint unlocking according to a second methodimplementation of the present disclosure. The method for fingerprintunlocking described in the implementation of the present disclosurestarts with operations at block 201.

At block 201, in response to detecting that a fingerprint recognitionmodule is pressed, whether a finger pressing the fingerprint recognitionmodule is a dry finger or a wet finger is determined.

In the implementation of the present disclosure, when a terminal detectsthat the fingerprint recognition module is pressed, the terminal candetermine whether fingerprints of the finger pressing the fingerprintrecognition module belong to (come from) a dry finger or a wet finger.Referring to FIG. 2A to FIG. 2C, FIG. 2A shows an example of fingerprintridges of a dry finger, FIG. 2B shows an example of fingerprint ridgesof a wet finger, and FIG. 2C shows an example of fingerprint ridges of anormal finger. With an understanding that fingerprint ridges in afingerprint image of a dry finger are intermittent and large-scalefingerprint ridges in a fingerprint image of a wet finger are blurredand almost indistinguishable, the fingerprint image can be analyzed todetermine whether the fingerprint image is from a dry finger or a wetfinger.

In an implementation, the terminal can extract ridge features of thefingerprint(s) of the finger pressing the fingerprint recognition moduleto determine whether the fingerprints are from a dry finger or a wetfinger. When the ridges in a fingerprint image are discontinuous, thefingerprint image is a fingerprint image of a dry finger. On thecontrary, when large-scale fingerprint ridges in a fingerprint image arefuzzy, the fingerprint image is a fingerprint image of a wet finger.

In an implementation, the terminal can extract the number of featurepoints of the fingerprint(s) of the finger pressing the fingerprintrecognition module and determine whether the number of the featurepoints falls within a preset range. The maximum value of the presetrange may be smaller than a first threshold. For example, the firstthreshold may be a certain percentage (for example, 50%) of the numberof the feature points of the preset fingerprint image, or the firstthreshold is a default value set by the system. Furthermore, values ofthe preset range may fall between a second threshold and a thirdthreshold, and the second threshold is smaller than the third threshold.The third threshold may be a certain percentage (for example, 50%) ofthe number of the feature points of the first fingerprint image, or thethird threshold is a default value set by the system. The secondthreshold may be a certain percentage (for example, 30%) of the numberof the feature points of the preset fingerprint image, or the secondthreshold is a certain system default value. In a normal situation, thenumber of feature points of a dry finger or a wet finger is smaller, andthe terminal can extract the number of feature points of thefingerprint. For example, when the number of feature points is less thanthe first threshold, it can be determined that the fingerprint is from adry finger or a wet finger.

Furthermore, when detecting that the fingerprint recognition module ispressed and the finger pressing the fingerprint recognition module isnot a dry finger or a wet finger, the terminal can obtain fingerprintimages by acquiring fingerprints through a default adjustment parameter,match the fingerprint image with the preset fingerprint image, andunlock the terminal when the match is successful.

At block 202, multiple fingerprint images are obtained, by acquiringmultiple sets of fingerprints through adjusting adjustment parameters ofa fingerprint acquisition chip of the fingerprint recognition modulemore than once, based on a determination that the finger pressing thefingerprint recognition module is a dry finger or a wet finger, whereeach fingerprint image corresponds to each set of fingerprints and theeach set of fingerprints corresponds to adjustment parameters adjustedeach time.

At block 203, a target fingerprint image with the best image quality isdetermined from the multiple fingerprint images.

At block 204, the terminal is unlocked when the target fingerprint imagematches a preset fingerprint image successfully.

For details of operations at block 202 to 204 described in FIG. 1B,reference can be made to descriptions of operations at block 101 to 103described in FIG. 1A, and will not be repeated here again.

By means of the implementations of the present disclosure, in responseto detecting that a fingerprint recognition module is pressed, multiplefingerprint images are obtained, by acquiring fingerprints throughadjusting adjustment parameters of a fingerprint acquisition chip of thefingerprint recognition module. Further, a target fingerprint image withthe best image quality from the multiple fingerprint images isdetermined. Then, a terminal is unlocked when the target fingerprintimage matches a preset fingerprint image successfully. Therefore, thetarget fingerprint image with the best image quality can be obtained byadjusting the adjustment parameters. When the target fingerprint imageis compared with the preset fingerprint image, the matching success ratebetween the two can be improved, that is, the efficiency of fingerprintunlocking can be improved. In particular, when the fingerprints of theuser's finger are fingerprints of a dry finger or fingerprints of a wetfinger, the number of times that the user presses the fingerprintrecognition module can be reduced, and thus, the efficiency offingerprint unlocking is improved, and time consumed by fingerprintunlocking is reduced.

Referring to FIG. 3A, FIG. 3A is a schematic flow chart illustrating amethod for fingerprint unlocking according to a third methodimplementation of the present disclosure. The method for fingerprintunlocking described in the implementation of the present disclosurestarts with operations at block 301.

At block 301, in response to detecting that a fingerprint recognitionmodule is pressed, whether a finger pressing the fingerprint recognitionmodule is a dry finger or a wet finger is determined.

At block 302, multiple fingerprint images are obtained, by acquiringmultiple sets of fingerprints through adjusting adjustment parameters ofa fingerprint acquisition chip of the fingerprint recognition modulemore than once, based on a determination that the finger pressing thefingerprint recognition module is a dry finger or a wet finger, whereeach fingerprint image corresponds to each set of fingerprints and theeach set of fingerprints corresponds to adjustment parameters adjustedeach time.

At block 303, a target fingerprint image with the best image quality isdetermined from the multiple fingerprint images by using at least oneimage quality evaluation index configured to evaluate fingerprintimages.

At block 304, the terminal is unlocked when the target fingerprint imagematches a preset fingerprint image successfully.

For details of operations at block 301 described in FIG. 3A, referencecan be made to descriptions of operations at block 201 described in FIG.1B. For details of operations at block 302 to 304 described in FIG. 3A,reference can be made to descriptions of operations at block 101 to 103described in FIG. 1A, and will not be repeated here again.

By means of the implementations of the present disclosure, in responseto detecting that a fingerprint recognition module is pressed, multiplefingerprint images are obtained, by acquiring fingerprints throughadjusting adjustment parameters of a fingerprint acquisition chip of thefingerprint recognition module. Further, a target fingerprint image withthe best image quality from the multiple fingerprint images isdetermined. Then, a terminal is unlocked when the target fingerprintimage matches a preset fingerprint image successfully. Therefore, thetarget fingerprint image with the best image quality can be obtained byadjusting the adjustment parameters. When the target fingerprint imageis compared with the preset fingerprint image, the matching success ratebetween the two can be improved, that is, the efficiency of fingerprintunlocking can be improved. In particular, when the fingerprints of theuser's finger are fingerprints of a dry finger or fingerprints of a wetfinger, the number of times that the user presses the fingerprintrecognition module can be reduced, and thus, the efficiency offingerprint unlocking is improved, and time consumed by fingerprintunlocking is reduced.

Referring to FIG. 3B, FIG. 3B is a schematic flow chart illustrating amethod for fingerprint unlocking according to a fourth methodimplementation of the present disclosure. The method for fingerprintunlocking described in the implementation of the present disclosurestarts with operations at block 401.

At block 401, whether fingerprint ridges of fingerprint images obtainedare discontinuous or fuzzy is determined, in response to a fingerprintrecognition module being detected to be pressed.

At block 402, multiple fingerprint images are obtained, by acquiringfingerprints more than once with any first adjustment level selectedfrom an analog-to-digital converter (ADC) offset including M firstadjustment levels and any second adjustment level selected from an ADCgain including N second adjustment levels, based on a determination thatthe fingerprint ridges of the fingerprint images obtained arediscontinuous or fuzzy. M and N are integers greater than 1.

At block 403, multiple image quality evaluation values are obtained, byperforming an image quality evaluation on each of the plurality offingerprint images according to one or more image quality evaluationindexes, and a fingerprint image corresponding to a maximum imagequality evaluation value is selected as a target fingerprint image. Theimage quality evaluation indexes include image clarity, signal-to-noiseratio (SNR), ridge resolution, fingerprint image coverage rate, contrastratio, and average gray scale.

At block 404, a terminal is unlocked when the target fingerprint imagematches a preset fingerprint image successfully.

Referring to FIG. 4, FIG. 4 is a schematic structural diagramillustrating a terminal according to a first terminal implementation ofthe present disclosure. The terminal 500 described in the implementationincludes a judging unit 501, an obtaining unit 502, a determining unit503, and an unlocking unit 504.

The judging unit 501 is configured to judge whether a finger pressing afingerprint recognition module is a dry finger or a wet finger, inresponse to the fingerprint recognition module being detected to bepressed.

The obtaining unit 502 is configured to obtain multiple fingerprintimages, by acquiring fingerprints more than once with any firstadjustment level selected from an analog-to-digital converter (ADC)offset including M first adjustment levels and any second adjustmentlevel selected from an ADC gain including N second adjustment levels,based on a determination that the finger pressing the fingerprintrecognition module is a dry finger or a wet finger. M and N are integersgreater than 1.

The determining unit 503 is configured to obtain multiple image qualityevaluation values, by performing an image quality evaluation on each ofthe plurality of fingerprint images according to one or more imagequality evaluation indexes, and select a fingerprint image correspondingto a maximum image quality evaluation value as a target fingerprintimage. The image quality evaluation indexes include image clarity,signal-to-noise ratio (SNR), ridge resolution, fingerprint imagecoverage rate, contrast ratio, and average gray scale.

The unlocking unit 504 is configured to unlock the terminal when thetarget fingerprint image determined by the determining unit matches apreset fingerprint image successfully.

As an implementation, the determining unit 503 is further configured todetermine, from the plurality of fingerprint images, the targetfingerprint image with the best image quality by using at least oneimage quality evaluation index configured to evaluate fingerprintimages.

As an implementation, the determining unit 503 is further configured to:calculate an image quality evaluation value of each fingerprint image ofthe plurality of fingerprint images with a formula

${S = {\sum\limits_{i = 1}^{K}{\partial_{i}P_{i}}}};$use a fingerprint image corresponding to a maximum image qualityevaluation value as the target fingerprint image.

S represents the image quality evaluation value, K represents the numberof the image quality evaluation indexes, P_(i) represents an imagequality evaluation value corresponding to the i^(th) image qualityevaluation index, ∂_(i) represents a weight of the i^(th) image qualityevaluation index, and

${\sum\limits_{i = 1}^{K}\partial_{i}} = 1.$

As an implementation, the judging unit 501 is configured to judgewhether the finger pressing the fingerprint recognition module is a dryfinger or a wet finger, in response to detecting that the fingerprintrecognition module is pressed.

The obtaining unit 502 is further configured to obtain the multiplefingerprint images, by acquiring the fingerprints through adjusting theadjustment parameters of the fingerprint acquisition chip of thefingerprint recognition module, when the judging unit 501 judges thatthe finger pressing the fingerprint recognition module is a dry fingeror a wet finger.

As an implementation, the judging unit 501 is further configured to:extract ridge features of a fingerprint of the finger pressing thefingerprint recognition module and judge whether the fingerprint belongsto a dry finger or a wet finger; or determine the number of featurepoints of the fingerprint of the finger pressing the fingerprintrecognition module and judge whether the number of feature points is ina preset range.

The above units can be realized through one or more processors, forexample, the above units can be integrated in one processor, or, can bedistributed among different processors.

By means of the terminal in the implementations of the presentdisclosure, in response to detecting that a fingerprint recognitionmodule is pressed, multiple fingerprint images are obtained, byacquiring fingerprints through adjusting adjustment parameters of afingerprint acquisition chip of the fingerprint recognition module.Further, a target fingerprint image with the best image quality from themultiple fingerprint images is determined. Then, a terminal is unlockedwhen the target fingerprint image matches a preset fingerprint imagesuccessfully. Therefore, the target fingerprint image with the bestimage quality can be obtained by adjusting the adjustment parameters.When the target fingerprint image is compared with the presetfingerprint image, the matching success rate between the two can beimproved, that is, the efficiency of fingerprint unlocking can beimproved. In particular, when the fingerprints of the user's finger arefingerprints of a dry finger or fingerprints of a wet finger, the numberof times that the user presses the fingerprint recognition module can bereduced, as such, the efficiency of fingerprint unlocking is improved,and time consumed by fingerprint unlocking is reduced.

FIG. 5 is a schematic structure diagram of a terminal according to asecond terminal implementation of the present disclosure. The terminal500 may include at least one input device 1000, at least one outputdevice 2000, at least one processor 3000 (such as a central processingunit (CPU)), and a computer readable storage 4000. The input device1000, the output device 2000, the processor 3000, and the computerreadable storage 4000 are coupled with each other via a bus 5000.

The input device 1000 may be a touch panel, a physical key, a mouse, afingerprint recognition module, etc.

The output device 2000 may be a display screen.

The computer readable storage 4000 may be a high-speed random accessmemory (RAM), or may be a non-volatile memory such as a disk memory. Thecomputer readable storage 4000 is configured to store a set of programcodes. The input device 1000, the output device 2000, the processor 3000are configured to call the program codes stored in the computer readablestorage 4000 to execute the following operations: obtaining multiplefingerprint images, by acquiring multiple sets of fingerprints throughadjusting adjustment parameters of a fingerprint acquisition chip of afingerprint recognition module more than once, in response to detectingthat the fingerprint recognition module is pressed, determining a targetfingerprint image with the best image quality from the multiplefingerprint images, and unlocking a terminal when the target fingerprintimage matches a preset fingerprint image successfully. Each fingerprintimage corresponds to each set of fingerprints and the each set offingerprints corresponds to adjustment parameters adjusted each time.

In an implementation, the adjustment parameters at least include ananalog-to-digital converter (ADC) offset and an ADC gain, the ADC offsetincludes M first adjustment levels, the ADC gain includes N secondadjustment levels, and M and N are integers greater than 1.

The processor 3000, configured to evoke the program codes stored in thememory to carry out the action of obtaining the multiple fingerprintimages, by acquiring multiple sets of the fingerprints through adjustingthe adjustment parameters of the fingerprint acquisition chip of thefingerprint recognition module more than once, is further configured toevoke the executable program codes stored in the memory to carry outactions: obtaining the multiple fingerprint images, by acquiring thefingerprints for several times with any first adjustment level selectedfrom the M first adjustment levels and any second adjustment levelselected from the N second adjustment levels.

In an implementation, the processor 3000, configured to evoke theexecutable program codes stored in the memory to carry out the action ofdetermining the target fingerprint image with the best image qualityfrom the multiple fingerprint images, is further configured to evoke theexecutable program codes stored in the memory to carry out actions:determining the target fingerprint image with the best image qualityfrom the multiple fingerprint images by using at least one image qualityevaluation index configured to evaluate fingerprint images.

In an implementation, the processor 3000, configured to evoke theexecutable program codes stored in the memory to carry out the action ofdetermining the target fingerprint image with the best image qualityfrom the multiple fingerprint images by using at least one image qualityevaluation index configured to evaluate fingerprint images, is furtherconfigured to evoke the executable program codes stored in the memory tocarry out actions: calculating an image quality evaluation value of eachfingerprint image of the multiple fingerprint images with a formula

${S = {\sum\limits_{i = 1}^{K}{\partial_{i}P_{i}}}},$and using a fingerprint image corresponding to a maximum image qualityevaluation value as the target fingerprint image.

S represents the image quality evaluation value, K represents the numberof the image quality evaluation indexes, P_(i) represents an imagequality evaluation value corresponding to the i^(th) image qualityevaluation index, ∂_(i) represents a weight of the i^(th) image qualityevaluation index, and

${\sum\limits_{i = 1}^{K}\partial_{i}} = 1.$

In an implementation, the processor 3000, is further configured to evokethe executable program codes stored in the memory to carry out actionsin response to detecting that the fingerprint recognition module ispressed: determining whether a finger pressing the fingerprintrecognition module is a dry finger or a wet finger and proceeding to theobtaining multiple fingerprint images, by acquiring multiple sets offingerprints through adjusting adjustment parameters of a fingerprintacquisition chip of a fingerprint recognition module more than once,based on a determination that the finger pressing the fingerprintrecognition module is a dry finger or a wet finger.

In an implementation, the processor 3000, configured to evoke theexecutable program codes stored in the memory to carry out the action ofdetermining whether the finger pressing the fingerprint recognitionmodule is a dry finger or a wet finger, is further configured to evokethe executable program codes stored in the memory to carry out one ofthe following actions: extracting ridge features of a fingerprint(s) ofthe finger pressing the fingerprint recognition module and determiningwhether the fingerprint belongs to a dry finger or a wet finger; anddetermining the number of feature points of the fingerprint(s) of thefinger pressing the fingerprint recognition module and judging whetherthe number of feature points is in a preset range.

In a specific implementation, the input device 1000, the output device2000, and the processor 3000 can be configured to implementimplementations described in the first, second and third implementationof the method for fingerprint unlocking of the implementations of thepresent disclosure. The input device 1000, the output device 2000, andthe processor 3000 can also be configured to implement implementationsdescribed in the first, second and third implementation of the terminalof the implementations of the present disclosure, which will not bedescribed in detail herein.

The implementations of the present disclosure also provide anon-transitory computer-readable storage medium. The non-transitorycomputer-readable storage medium stores computer programs which, whenexecuted, by a processor, causes the processor to carry out all or partof the actions of any method for fingerprint unlocking described in theabove-described method implementations.

In the foregoing implementations, the description of each implementationhas its own emphasis. For the parts not described in detail in oneimplementation, reference may be made to related descriptions in otherimplementations.

It is to be noted that, for the sake of simplicity, the foregoing methodimplementations are described as a series of action combinations,however, it will be appreciated by those skilled in the art that thepresent disclosure is not limited by the sequence of actions described.According to the present disclosure, certain steps or operations may beperformed in other order or simultaneously. Besides, it will beappreciated by those skilled in the art that the implementationsdescribed in the specification are exemplary implementations and theactions and modules involved are not necessarily essential to thepresent disclosure.

In the implementations of the disclosure, the apparatus disclosed inimplementations provided herein may be implemented in other manners. Forexample, the device/apparatus implementations described above are merelyillustrative; for instance, the division of the unit is only a logicalfunction division and there can be other manners of division duringactual implementations, for example, multiple units or components may becombined or may be integrated into another system, or some features maybe ignored, omitted, or not performed. In addition, coupling orcommunication connection between each illustrated or discussed componentmay be direct coupling or communication connection, or may be indirectcoupling or communication among devices or units via some interfaces,and may be electrical connection, mechanical connection, or other formsof connection.

The units described as separate components may or may not be physicallyseparated, the components illustrated as units may or may not bephysical units, that is, they may be in the same place or may bedistributed to multiple network elements. All or part of the units maybe selected according to actual needs to achieve the purpose of thetechnical solutions of the implementations.

In addition, the functional units in various implementations of thepresent disclosure may be integrated into one processing unit, or eachunit may be physically present, or two or more units may be integratedinto one unit. The above-mentioned integrated unit can be implemented inthe form of hardware or a software function unit.

The integrated unit may be stored in a computer-readable memory when itis implemented in the form of a software functional unit and is sold orused as a separate product. Based on such understanding, the technicalsolutions of the present disclosure essentially, or the part of thetechnical solutions that contributes to the related art, or all or partof the technical solutions, may be embodied in the form of a softwareproduct which is stored in a memory and includes instructions forcausing a computer device (which may be a personal computer, a server,or a network device and so on) to perform all or part of the stepsdescribed in the various implementations of the present disclosure. Thememory includes various medium capable of storing program codes, such asa USB (universal serial bus) flash disk, a read-only memory (ROM), arandom-access memory (RAM), a removable hard disk, Disk, compact disc(CD), or the like.

It will be understood by those of ordinary skill in the art that all ora part of the various methods of the implementations described above maybe accomplished by means of a program to instruct associated hardware,the program may be stored in a computer-readable memory, which mayinclude a flash memory, a read-only memory (ROM), a random-access memory(RAM), Disk or compact disc (CD), and so on.

While the present disclosure has been described in detail above withreference to the exemplary implementations, the scope of the presentdisclosure is not limited thereto. As will occur to those skilled in theart, the present disclosure is susceptible to various modifications andchanges without departing from the spirit and principle of the presentdisclosure. Therefore, the scope of the present disclosure should bedetermined by the scope of the claims.

What is claimed is:
 1. A method for fingerprint unlocking, comprising:determining whether fingerprint ridges of fingerprint images obtainedare discontinuous or fuzzy, in response to a fingerprint recognitionmodule being detected to be pressed; obtaining a plurality offingerprint images, by acquiring fingerprints more than once with anyfirst adjustment level selected from an analog-to-digital converter(ADC) offset comprising M first adjustment levels and any secondadjustment level selected from an ADC gain comprising N secondadjustment levels, based on a determination that the fingerprint ridgesof the fingerprint images obtained are discontinuous or fuzzy; M and Nbeing integers greater than 1; obtaining a plurality of image qualityevaluation values, by performing an image quality evaluation on each ofthe plurality of fingerprint images according to one or more imagequality evaluation indexes, and selecting a fingerprint imagecorresponding to a maximum image quality evaluation value as a targetfingerprint image; the image quality evaluation indexes comprising imageclarity, signal-to-noise ratio (SNR), ridge resolution, fingerprintimage coverage rate, contrast ratio, and average gray scale; andunlocking a terminal when the target fingerprint image matches a presetfingerprint image successfully.
 2. The method of claim 1, whereindetermining the target fingerprint image with the best image qualityfrom the plurality of fingerprint images comprises: determining thetarget fingerprint image with the best image quality from the pluralityof fingerprint images by using at least one image quality evaluationindex configured to evaluate fingerprint images.
 3. The method of claim2, wherein determining the target fingerprint image with the best imagequality from the plurality of fingerprint images by using the at leastone image quality evaluation index configured to evaluate fingerprintimages comprises: calculating an image quality evaluation value of eachfingerprint image of the plurality of fingerprint images with a formula${S = {\sum\limits_{i = 1}^{K}{\partial_{i}P_{i}}}};$ and using afingerprint image corresponding to a maximum image quality evaluationvalue as the target fingerprint image; S representing the image qualityevaluation value, K representing the number of the image qualityevaluation indexes, P_(i) representing an image quality evaluation valuecorresponding to the i^(th) image quality evaluation index, ∂_(i)representing a weight of the i^(th) image quality evaluation index, and${\sum\limits_{i = 1}^{K}\partial_{i}} = 1.$
 4. The method of claim 3,further comprising the following in response to detecting that thefingerprint recognition module is pressed: judging whether a fingerpressing the fingerprint recognition module is a dry finger or a wetfinger; proceeding to obtaining the plurality of fingerprint images, byacquiring fingerprints through adjusting adjustment parameters of afingerprint acquisition chip of the fingerprint recognition module,based on a judgment that the finger pressing the fingerprint recognitionmodule is a dry finger or a wet finger.
 5. The method of claim 4,wherein judging whether the finger pressing the fingerprint recognitionmodule is the dry finger or the wet finger comprises one of: extractingridge features of a fingerprint of the finger pressing the fingerprintrecognition module and judging whether the fingerprint belongs to a dryfinger or a wet finger; and determining the number of feature points ofthe fingerprint of the finger pressing the fingerprint recognitionmodule and judging whether the number of feature points is in a presetrange.
 6. A terminal, comprising: a memory storing executable programcodes; a processor coupled with the memory; the processor beingconfigured to evoke the executable program codes stored in the memoryto: determine whether fingerprint ridges of fingerprint images obtainedare discontinuous or fuzzy, in response to a fingerprint recognitionmodule being detected to be pressed; obtain a plurality of fingerprintimages, by acquiring fingerprints more than once with any firstadjustment level selected from an analog-to-digital converter (ADC)offset comprising M first adjustment levels and any second adjustmentlevel selected from an ADC gain comprising N second adjustment levels,based on a determination that the fingerprint ridges of the fingerprintimages obtained are discontinuous or fuzzy; M and N being integersgreater than 1; obtain a plurality of image quality evaluation values,by performing an image quality evaluation on each of the plurality offingerprint images according to one or more image quality evaluationindexes, and selecting a fingerprint image corresponding to a maximumimage quality evaluation value as a target fingerprint image; the imagequality evaluation indexes comprising image clarity, signal-to-noiseratio (SNR), ridge resolution, fingerprint image coverage rate, contrastratio, and average gray scale; and unlock a terminal when the targetfingerprint image matches a preset fingerprint image successfully. 7.The terminal of claim 6, wherein the processor, configured to evoke theexecutable program codes stored in the memory to determine the targetfingerprint image with the best image quality from the plurality offingerprint images is further configured to evoke the executable programcodes stored in the memory to: determine the target fingerprint imagewith the best image quality from the plurality of fingerprint images byusing at least one image quality evaluation index configured to evaluatefingerprint images.
 8. The terminal of claim 7, wherein the processor,configured to evoke the executable program codes stored in the memory todetermine the target fingerprint image with the best image quality fromthe plurality of fingerprint images by using the at least one imagequality evaluation index configured to evaluate fingerprint images isfurther configured to evoke the executable program codes stored in thememory to: calculate an image quality evaluation value of eachfingerprint image of the plurality of fingerprint images with a formula${S = {\sum\limits_{i = 1}^{K}{\partial_{i}P_{i}}}};$ and use afingerprint image corresponding to a maximum image quality evaluationvalue as the target fingerprint image; S representing the image qualityevaluation value, K representing the number of the image qualityevaluation indexes, P_(i) representing an image quality evaluation valuecorresponding to the i^(th) image quality evaluation index, ∂_(i)representing a weight of the i^(th) image quality evaluation index, and${\sum\limits_{i = 1}^{K}\partial_{i}} = 1.$
 9. The terminal of claim 8,wherein the processor is further configured to evoke the executableprogram codes stored in the memory to, in response to detecting that thefingerprint recognition module is pressed: judge whether a fingerpressing the fingerprint recognition module is a dry finger or a wetfinger; proceed to obtaining the plurality of fingerprint images, byacquiring fingerprints through adjusting adjustment parameters of afingerprint acquisition chip of the fingerprint recognition module,based on a judgment that the finger pressing the fingerprint recognitionmodule is a dry finger or a wet finger.
 10. The terminal of claim 9,wherein the processor, configured to evoke the executable program codesstored in the memory to judge whether a finger pressing the fingerprintrecognition module is a dry finger or a wet finger is further configuredto evoke the executable program codes stored in the memory to: extractridge features of a fingerprint of the finger pressing the fingerprintrecognition module and judge whether the fingerprint belongs to a dryfinger or a wet finger; and determine the number of feature points ofthe fingerprint of the finger pressing the fingerprint recognitionmodule and judge whether the number of feature points is in a presetrange.